ᐅ Building Drying: Is It Better to Turn Off the Controlled Mechanical Ventilation System in Summer?

I can’t imagine that this would help.
A mechanical ventilation system with heat recovery also removes moisture from the air, not from the building fabric – a construction dryer has a completely different function, in my opinion.

Best regards in brief

Our screed is currently drying. At the moment, it can be walked on but not yet covered.
Our mechanical ventilation system is not running! Our underfloor heating is working, but nothing more. The site manager told us that we should manually ventilate twice a day. Open everything on the east side in the basement and on the west side upstairs. Always for 15 minutes.
Warm air inside the house can absorb more moisture than cold air. That is the reason behind this.

Alex85 schrieb:
I thought the mechanical ventilation system should only be turned on after the building drying phase, due to contamination and the constantly high humidity in the system at the beginning... this was discussed somewhere before.

Correct. The system is only put into operation at a later stage. During the shell construction phase, there is simply too much dust in the air. The system and ducts would only become unnecessarily contaminated. You would definitely need some filters installed on the main unit. Besides, the airflow rate of the mechanical ventilation system is simply too low for building drying.

I would just leave it off and instead keep a window slightly open upstairs. That provides better airflow and is more cost-effective. 🙂

Payday schrieb:


I would skip that and just tilt a window open on the upper floor. It allows more airflow and is cheaper 🙂

Hello,
that doesn’t make any sense with the current weather (daytime over 20°C (68°F) and at least 80% humidity).
The installed dehumidifiers dry the incoming outside air.

Kind regards, Barossi

If you are using dehumidifiers and the humidity is already as low as you mentioned in the other thread, additional measures to reduce moisture won’t have any effect. You have already minimized the vapor pressure in the room air. The drying of the screed (or other materials) depends on the vapor pressure difference. The only way to speed up drying now is to increase the vapor pressure in the screed itself, which means heating it.

Circulation, for example with fans, might help if humidity levels vary significantly from room to room.

Hello,
yes, I think so too. I have installed 3 large dehumidifiers, all heating systems turned up to maximum, and windows closed.

The place is barely bearable: 34°C (93°F) and about 30% humidity in most rooms. I have to empty the containers almost 3 times a day. Fans will be provided next week; I read that they can help a bit more.

Do the fans need to blow the air over the screed towards the dehumidifiers?

When the outdoor temperature drops below 10°C (50°F) again with normal humidity (at least under 80%), I will ventilate briefly.
The plumber will be at the house again next week, let’s see, he will probably complain because it’s way too hot to work!

Best regards, Barossi